How to brighten this cottage?

Definitely paint

Painting the panelling would brighten the room up and make it look more modern, I’d be tempted to leave the fireplace and all doors as they are though for a contrast.

Sounds like a couples issue to me !! IMO , it's kind of a shame to paint that beautiful old , looks like tongue and groove , paneling , lots of charm . Maybe paint one wall ? Think I'd leave well enough alone and maintain cottage charm , use brighter upholstery , wall hangings , rugs , table lamps , etc

0nce the walls are painted there's no going back !

Bright wall hangings if painting is a no go. I would also replace the brown sofa with a lighter color.

Go half and half. Restrain the wood a lighter color and paint the top hang.

maybe keep wood at the bottom, add a chair rail and sheet rock to the top and paint! He gets the wood look and you get an open airy cleaned up look!

Use the wood to your advantage! What you really need here are some coordinated contrasts in color. I would compromise by painting (ahh!) the fireplace wall in a pastel that will compliment both the hearth and whatever contrasting colors you choose to decorate with. Then really 'work it' with your walls. Sheers in that burgundy on your couch over the three windows to the right, maybe a nice patterned valance on the far window. Definitely shelves on the near corner of the long wall with all kinds of 'beachy' knickknacks. Hangings (from a decorative fish net), or a photo gallery behind the chairs. Maybe a colorfully designed rug under the coffee table. Oh, and don't forget some plants! Even silks will work if you aren't there all the time to keep them alive. Green plants and colorful flowers ALWAYS bring life into a room.

How about painting the ceiling? That would make the room seem much lighter, larger and airier and might not upset your hubby too much!

Bring in different size lamps don't replace furniture, make or buy furniture covers/ protectors in light colors like beige, soft yellow, baby blue or any other colors you'd prefer. Buy textured pillows, you could even brighten your place with a light, room size rug and pull it all together with plants and decorative pieces like wall art, vases, statues etc!

We have mahogany walls in two rooms, but didn't want to paint them... they're so pretty! So we decided to paint the trim of the room and windows, as well as the doors, white. It gives it a Cape Cod look, but leaves the beautiful wood walls.